In the manufacture of a semiconductor device, a process called bevel etching is performed to remove an unnecessary film from a peripheral portion of a substrate such as a semiconductor wafer including a bevel portion thereof by using a chemical liquid. A film required to be left often exists under the film required to be removed. In this case, if etching selectivity of the film required to be removed against the film required to be left is not sufficiently high, an etching rate needs to be suppressed low in order to minimize an etching amount of the film required to be left.
Described in Patent Document 1 is a substrate processing method of performing bevel etching. In this method, when the etching rate needs to be increased, a high-concentration chemical liquid such as hydrofluoric acid is supplied to a peripheral portion of a substrate being rotated from a first nozzle. When the etching rate needs to be reduced, on the other hand, pure water (DIW) is supplied to the peripheral portion of the substrate from a second nozzle while the high-concentration chemical liquid is being supplied from the first nozzle to the peripheral portion of the substrate being rotated, so that the chemical liquid supplied from the first nozzle can be diluted.
However, this method of controlling the etching rate by the combination of the hydrofluoric acid and the pure water may not be applicable to a case where the removing target film is made of SiGe, amorphous silicon or polysilicon.